Shorthanded Hold'em: sometimes they beg you to take their money

There are many good players in shorthanded online games, but there are also some astoundingly bad players. Here's a hand in a 6 max 10/20 game. My opponent's call on the Turn makes me scratch my head.

Preflop: Yao is SB with As, Kc.
2 folds, Button raises, Yao 3-bets, 1 fold, Button caps, Yao calls.

He capped it pre-Flop. I'm hoping he has a weaker Ace, or if he has a pair that I hit a pair on the board.

Flop: (9 SB) 2c, 4h, Ah (2 players)
Yao checks, Button bets, Yao calls.

I decide not to make it too obvious that I have an Ace. I decide I'll check-raise him on the Turn unless a scare card comes, in which case I'll just bet out.

Turn: (5.50 BB) 3h (2 players)
Yao bets, Button calls.

The 3h is a scary card, making a possible straight and a three-flush. I'm worried that this Turn card will stop him from betting if I check. So I abandon my plan to check-raise on the Turn and bet out instead. I'm worried that he'll check if I check because there is now a three-flush and a four-straight, as well as an Ace. If he has a pair of K's, he's probably going to check behind (unless one of his K's is a heart). If it was a different card, say the 2d instead of the 3h, I think there would have been a much better chance that he would bet if I checked. Once he calls, I'm worried that he has a heart. I'm hoping he's got a weak Ace or a pair without a heart.

River: (7.50 BB) Kh (2 players)
Yao checks, Button checks.

I could have bet, I think betting and checking are very close here. But I decided to check and call. I figured there was a good chance he had a pair, and seeing the King on the River, he'd only call if he had a heart. So he's not likely to pay me off with JJ, TT; but he'd definitely call with a heart. The negatives in checking is that I forgo the chance of picking up an extra bet if he has an Ace without a heart. But the check gets me the possible chance of a bluff bet on the River (an incorrect bluff bet, but possible too). Its really tough to weigh which is better, checking or betting, as there are so many variables. If I work out this problem and assume some possible hands my opponent could be holding, I'd come up with an expected value of checking or betting and compare which is better. But as you will see from the results, doing an EV analysis is sometimes moot because the assumptions are sometimes difficult to pinpoint.

Final Pot: 7.50 BB
Results below: Yao has As Kc (two pair, aces and kings). Button has Ts Ks (one pair, kings). Outcome: Yao wins 7.50 BB.

So he called a bet on the Turn with KsTs when the board was 2c 4h Ah 3h. Given that he called me on the Turn, he probably would have called the River bet since he made a pair of Kings. So in retrospect, I missed a bet on the River. If I had done a EV analysis of what is better - checking or betting on the River, I would never have assumed he held a hand like KT without a heart. After the hand, I hit up the hand history and I was shocked to see what he had.